1. FIELD OF THE INVENTION
This invention relates generally to video response devices such a video games and video learning systems; and more particularly to a very inexpensive apparatus for registering responses to video images displayed by a standard video tape player and television receiver.
2. PRIOR ART
Arcade and home video games--and video learning systems--produced by computer, using images displayed on a computer monitor, are well known. A computer employed for such purposes in some cases is a dedicated "game computer," using software either permanently embedded in the computer or carried in cartridges; and in other cases is a general-purpose personal computer using game software read into the machine memory by floppy discs or the like.
Some such games make use of an ordinary television receiver set, connected to receive signals from the computer. In this type of game the television receiver may be modified to receive signals from the computer rather than from a conventional video source.
Although many video games and learning systems use input responses from a keyboard or a joystick, some are based on the concept of aiming a "gun" or the like at a target displayed on the screen. In these games the computer--and through it the computer monitor or television receiver--receive signals from the gun, and these signals are used to determine the accuracy of aim.
Results of this determination are used interactively by the programmed computer to generate and display effects on the screen, indicating where the gun was in fact pointed and in some cases also changing the screen display when the gun was aimed correctly. Further, scores are developed by the computer and fed back to the monitor or receiver screen for display along with the target display.
Various electrooptical schemes have been used to determine the part of the screen at which the gun is pointed. In one type of system, signals from a sensing circuit in the gun are compared with the phase of the vertical and horizontal raster-drive pulses to determine the position of the video electron beam at the instant it passes the gunsight. This comparison provides a very accurate location, but of course requires special wiring to pass synchronizing signals between the video display and the sensing circuit and computer analyzer.
In another type of system, the target is displayed as, for example, a light spot on a darker screen. The only light pulses that can come from the screen must therefore originate from the target spot. The gun receives and is programmed to respond to these light pulses. This system has the drawback that it is restricted to use with a relatively dark and static background displayed on the screen.
This system is also subject to interfering effects of extraneous optical signals in the room or other area where the game is used. These can be screened out by sensitizing the analysis circuit to pulses that contain the video line scanning frequency, or that occur at the scanning repetition rate, or both.
One such system is described by Steiger and Wahl in U.S. Pat. No. 4,205,847; they seem to suggest (column 3, lines 8 through 18) that such sensitization should be accomplished by synchronous demodulation. That technique, here again, is very accurate but requires wiring between the gun and the video-display unit for the synchronization.
In the past such wiring has been perhaps a slight nuisance in handling of the gun or other aiming unit. This is especially true for units that are best aimed from across a room, and for games in which two or more players pass the aiming unit back and forth.
Nevertheless such wiring has not been considered a great drawback, since connections for producing "hit" and scoring displays on the screen were desired anyway. More recently, however, the considerable cost of dedicated game computers--or of providing special circuitry for game adaptation of standard television sets--has made such wired-in systems unappealing in the market.
In a variant of this type of system, hard wiring between the gun or other aiming unit and the display screen is eliminated in favor of an infrared-beam or other wireless transmission of hit information to an electronics package that is part of the computer, attached to the screen. This variant is described in another patent of Steiger and Wahl, U.S. Pat. No. 4,210,329.
This approach does improve convenience in use of a target game, but as will be apparent it does not alleviate the considerable cost and cumbersomeness of providing and connecting the computer-and-electronics unit to serve as a game adapter for the video-display unit.
On the other hand, there is a different type of problem also associated with prior video target-game systems and video learning systems. As a general rule, the number of players who can play a particular game at the same time is limited.
This is effectively true even for the remote response unit of Steiger and Wahl, since the limiting factor arises in the number of inputs which the scoring system can handle within the framework of a single game. Interestingly, as a practical matter this limitation of the number of players is nearly independent of cost considerations, since game systems capable of receiving more than a very few simultaneous sets of inputs are essentially not on the market.
Another prior patent that may be related to our invention, although it appears to be in a different field, is U.S. Pat. No. 4,243,972 to Toussaint. That patent relates to identifying targets "among a field or group of targets"--and more particularly to distinguishing among such targets.
The Toussaint patent does not appear, however, to relate to games or learning systems, but rather to a video monitor used in lieu of a keyboard as an input device for a computer. For this purpose the monitor is used in combination with a light pen that is applied directly to the screen.
Such apparatus is well known in the context of computer systems for control of industrial process plants. In that context the various "targets" are simply used in place of keyboard keys, with the advantage that they can be superposed on diagrams of the plant piping or wiring.
The various targets can then represent various valves or switches to be operated remote-control by a plant operator at the video display, or for example they can represent various parts of the plant which the operator might like to see diagrammed in greater detail. The implication of touching the light pen to different parts of the screen thus varies with the portion of the system diagrammed on the screen.
Toussaint's disclosure suggests that it is such a system he has in mind. He says (column 4, lines 7 through 12, and lines 53 through 64; emphasis added): "By allowing the computer to recognize which character, area or location on the face of the CRT 1 has been selected by the positioning of pen 4, this method and apparatus makes [sic] possible a computer-user interaction without the need for other forms of user input devices . . .
"[T]he method entails . . . application of the pen to a selected target, area or location of the CRT screen . . . to control the computer."
Such a system as part of a process-plant control system may be typically priced upward of $100,000. It will be clear in any event that the Toussaint patent is not directed to the field of video games or learning systems.
From Toussaint's disclosure it is not clear why his targets are not simply distinguished from one another, as described above, by position of the raster beam. That is to say, his targets could have been identified by the phase of the vertical and horizontal san pulses--since his computer is hard-wired to his monitor anyway.
At the time of Toussaint's invention, however, the electronic hardware needed for real-time determination of raster phase was too new for use in a practical industrial system. Toussaint instead developed a system of coding the light pulses from his targets, for recognition by circuitry connected to his light pen. The "pen," really an optical receiver, is actuated by a lightly spring-loaded switch element, in the tip, adapted to be touched to the video screen.
His computer is programmed to cancel or suppress particular electron-beam scans, at the locations of multiple targets, thereby producing an "on-off status or blinking pattern" there. Different blinking patterns are used for different target areas, and the computer is programmed to analyze the signal from the optical receiver--testing for the particular blinking patterns in use.
None of the above patents suggests combining such coding with games (or learning systems) such as those of Steiger and Wahl. Further, none of these patents suggests that there could be any way to provide a video target game without attaching a game computer to a video display unit.
Yet there is a demand in the market for particularly economical video target games that can be used in the home without the cost and cumbersomeness of special wiring connections. The prior art fails to satisfy this demand.